Walk-in bathtubs comprise high tub walls with a high built in seat and a side door, allowing the user to walk into the tub from the side and sit down without having to climb down into a low bath tub. FIG. 1 shows a typical example of a walk-in bathtub in accordance with the prior art. Walk-in tubs are particularly suited for individuals who have physical limitations that make it difficult or dangerous to climb into and out of a regular, low bathtub or to stand up in a shower for extended periods of time. Such limitations might include physical disabilities or simply the reduced strength, balance and range of motion that typically occur with advancing age. Walk-in tubs are not only easier to enter and exit than conventional bathtubs they also reduce the chances of slips and falls compared to conventional tubs and showers.
In addition to safety, the ease of entering the tub via the side walk-in door also provides users with independence, allowing them to bathe without the assistance of another person when getting into and out of the tub.
However, because of their depth, walk-in bathtubs hold very large volumes of water. With seat heights approaching 17 inches above the tub floor water volume can reach 70 gallons or more. Typically, such large volumes require up to seven minutes to drain from the tub. This is particularly troublesome in the case of walk-in bathtubs because the occupant cannot open the side door and exit the tub until the water has drained, especially in models in which the side door opens to the inside and is held shut by water pressure.
Therefore it would be desirable to have a mechanism that speeds the drain time of walk-in baths beyond what is possible with simple gravity draining.